Struct OverlayReservation 

pub struct OverlayReservation { /* private fields */ }

Overlay planes claimed for decorations, per CRTC.

Implementations

impl OverlayReservation

pub fn new() -> Self

An empty reservation.

pub fn reserve( &mut self, registry: &PlaneRegistry, crtc_index: u32, fourcc: u32, count: usize, min_zpos: u64, ) -> Result<Vec<u32>, ReserveError>

Claim count overlay planes on crtc_index that can scan out fourcc.

Returns them in ascending zpos order, which is the order a caller stacks decorations in: the lowest is the one behind.

min_zpos excludes planes that cannot sit above the window. A decoration below the content it decorates is invisible, so a caller that knows the window’s stacking position passes it here rather than discovering the problem on screen.

Re-reserving a CRTC releases what it held first — except with a count of zero, which, as upstream, returns early and leaves an existing claim in place. A caller responding to a mode change asks again with a new count, and the old claim would otherwise keep planes it no longer wants out of everyone else’s reach; to give them all up, call release.

Errors

ReserveError::Shortfall when fewer than count planes match. This CRTC’s previous claim has already been released and nothing new is claimed — no partial fill: a caller that asked for three and got two would have to work out which of its decorations to drop.

pub fn release(&mut self, crtc_index: u32)

Give back everything this CRTC holds.

A CRTC that holds nothing, or was never reserved for, is a no-op — both are what a caller tearing down an output does, sometimes twice.

pub fn reserved_for(&self, crtc_index: u32) -> &[u32]

What this CRTC holds, in zpos order.

pub fn all_reserved(&self) -> Vec<u32>

Every claimed plane, across every CRTC.

What goes to Allocator::set_reserved_planes, which is why it is one list rather than a map: the allocator is told which planes it may not have, and it does not care who has them.

Trait Implementations

impl Debug for OverlayReservation

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for OverlayReservation

fn default() -> Self

Returns the “default value” for a type.